1. health and fitness
2. disease
3. cancer

Outcomes after stereotactic body radiotherapy for
lung tumors, with emphasis on comparison of primary
lung cancer and metastatic lung tumors
Takaya Yamamoto1*, Keiichi Jingu1, Yuko Shirata1, Masashi Koto2, Haruo
Matsushita1, Toshiyuki Sugawara1, Masaki Kubozono1, Rei Umezawa1, Keiko Abe1,
Noriyuki Kadoya1, Youjirou Ishikawa1, Maiko Kozumi1, Noriyoshi Takahashi1, Ken
Takeda3 and Yoshihiro Takai4
1
Department of Radiation Oncology, Tohoku University School of Medicine, Sendai,
Japan
2
Research Center for Charged Particle Therapy, National Institute of Radiological
Sciences, Chiba, Japan
3
Department of Radiological Technology, School of Health Sciences, Faculty of
Medicine, Tohoku University, Sendai, Japan
4
Department of Radiation Oncology, Hirosaki University School of Medicine,
Aomori, Japan
* Corresponding author
Email addresses:
Takaya Yamamoto: t.yamamoto@rad.med.tohoku.ac.jp
Keiichi Jingu: kjingu-jr@rad.med.tohoku.ac.jp
Yuko Sshirata: guldoktu@yahoo.co.jp
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Masashi Koto: koto@nirs.go.jp
Haruo Matsushita: harumatsu2001@yahoo.co.jp
Toshiyuki Sugawara: sugatosi772288@yahoo.co.jp
Masaki Kubozono: satoharuapple@yahoo.co.jp
Rei Umezawa: reirei513@hotmail.com
Keiko Abe: abe-k@rad.med.tohoku.ac.jp
Noriyuki Kadoya: kadoya.n@rad.med.tohoku.ac.jp
Youjirou Ishikawa: y02614111@yahoo.co.jp
Maiko Kozumi: drmk2009@yahoo.co.jp
Noriyoshi Takahashi: noriyoshi.08.25@gmail.com
Ken Takeda: takedak41@yahoo.co.jp
Yoshihiro Takai: takaiken@ic-net.or.jp
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Abstract
Background
The goal of this study was to determine the prognostic factors associated with an
improved overall outcome after stereotactic body radiotherapy (SBRT) for primary
lung cancer and metastatic lung tumors.
Methods
A total of 229 lung tumors in 201 patients were included in the study. SBRT of 45 Gy
in 3 fractions, 48 Gy in 4 fractions, 60 Gy in 8 fractions or 60 Gy in 15 fractions was
typically used to treat 172 primary lungs cancer in 164 patients and 57 metastatic lung
tumors in 37 patients between January 2001 and December 2011. Prognostic factors
for local control (LC) and overall survival (OS) were analyzed using a Cox
proportional hazards model.
Results
The median biologically effective dose was 105.6 Gy based on alpha/beta = 10
(BED10). The median follow-up period was 41.9 months. The 3-year LC and OS
rates were 72.5% and 60.9%, and the 5-year LC and OS rates were 67.8% and 38.1%,
respectively. Radiation pneumonitis of grades 2, 3 and 5 occurred in 22 petients, 6
patients and 1 patient, respectively. Multivariate analyses revealed that tumor origin
(primary lung cancer or metastatic lung tumor, p<0.001), tumor diameter (p=0.005),
BED10 (p=0.029) and date of treatment (p=0.011) were significant independent
predictors for LC and that gender (p=0.012), tumor origin (p=0.001) and tumor
diameter (p<0.001) were significant independent predictors for OS.
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Conclusions
SBRT resulted in good LC and tolerable treatment-related toxicities. Tumor origin
and tumor diameter are significant independent predictors for both overall survival
and local control.
Keywords
Stereotactic radiotherapy; SBRT; Primary lung cancer; Metastatic lung tumor;
Oligometastasis; Prognostic factor
Background
Stereotactic body radiotherapy (SBRT) results in a high local control rate for
relatively small lung tumors and has low treatment-related toxicity, and it thus has
many benefits for patients, especially patients who cannot undergo surgery [1-3].
SBRT may also be beneficial for patients who choose not to undergo surgery. For
example, elderly patients, even elderly patients with no or only a few comorbidities
and moderate lung function, often hesitate to undergo surgery because of concerns
about postoperative complications, decline in activities of daily living, and
progression of dementia, even in short-term admission. A time-trend analysis in the
Netherlands showed that the number of elderly patients treated with radiotherapy for
stage I non-small-cell lung cancer (NSCLC) has been increasing over time. This has
occurred in parallel with increased availability of SBRT and has led to a decrease in
untreated patients and no increase in surgically treated patients, despite operative and
perioperative advances such as video-assisted thoracic surgery [4]. Furthermore, the
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outcome for stage I NSCLC treated with SBRT is now close to that after lobectomy,
based on the results of a recent propensity-score matched analysis [5].
Retrospective analyses and one prospective analysis of SBRT for oligometastatic
lung tumors have shown 2- to 3-year survival rates with good local control (LC) that
compare favorably with surgical results [2-3]. If SBRT has an efficacy comparable to
that of tumor resection, this technique may provide patients with a better quality of
life, shorter time away from work, and minimal interruption of other treatment. This
third issue may be a major advantage because systemic chemotherapy is often
performed for targeting oligometastatic lung tumors, treating another lesion, or as
maintenance or consolidation therapy for potential metastases.
Recently, the new notion of oligo-recurrence was proposed because the initial
concept of oligometastases did not eliminate the uncontrolled primary site with
several distant metastases. Oligo-recurrence has been suggested as a state of
metachronous limited recurrence or metastases possibly cured with local therapy [6].
SBRT for lung oligo-recurrence with good LC rate and survival rate has also been
reported [7].
Many prognostic factors for LC after SBRT have been reported, including tumor
diameter, standardized uptake value (SUV) on [18F]fluorodeoxyglucose positron
emission tomography (FDG-PET), low dose distribution, metastatic lung tumors, and
colorectal lung metastases [8-14]. In contrast, there have been only a few studies in
which prognostic factors for overall survival (OS) were examined, though
clarification of such factors is important to maximize the benefit/toxicity ratio [1416]. In this study, we retrospectively reviewed our results for lung tumors treated with
SBRT with the goal of identifying prognostic factors associated with LC and OS and
thus establishing a strategy for balancing the benefits and risks in use of SBRT.
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Methods
Patients
A review of our institutional clinical database identified 215 patients who were
treated with SBRT at our institute between January 2001 and December 2011.
Patients with follow-up of <3 months were excluded, leaving a total of 229 lung
tumors in 201 patients that were analyzed retrospectively. Of these, 172 tumors in 164
patients were stage I primary lung cancer and 57 tumors in 37 patients were metastatic
tumors. The main clinical and pathological pretreatment features are summarized in
Tables 1 and 2. All numerical data are expressed as medians. The histological
diagnoses of the 172 cases of primary lung cancer were adenocarcinoma (56 tumors),
squamous cell carcinoma (40 tumors), large cell carcinoma (10 tumors), small cell
carcinoma (2 tumors), NSCLC not otherwise specified (5 tumors), and
bronchioloalveolar carcinoma (2 tumors), and 57 tumors were pathologically
unproven. A metastatic lung tumor was defined as the appearance of a solid tumor
during follow-up after treatment for the primary lesion. Inclusion criteria of metastatic
tumors were that tumor diameter was 5 cm or less, both radiation oncologists and the
physician assessed that SBRT of metastatic tumors would yield improved systemic
control and prolonged survival, and consequently, all of the primary sites were
controlled. Thirty-five cases were surgically resected, one case was esophageal cancer
controlled by chemoradiation and another case was hepatocellular carcinoma
controlled by transarterial chemoembolization. Two cases were synchronous
metastases with a primary lesion, and 6 cases received additional chemotherapy.
Biopsy for a metastatic lung tumor was performed only during follow-up of double
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cancer. Of the 57 metastatic tumors, 29 were metastases from colorectal cancer and
28 were metastases from other malignancies.
SBRT procedure
We previously reported details of our SBRT technique and follow-up studies in
patients with primary lung cancer [18]. Each patient was immobilized in a body frame
(Vac-loc, Med-tek) and a clinician observed the respiratory tumor motion on a
simulator (Ximatron, Varian Medical Systems). If breathing motion had a large effect
on the tumor location, the clinician made the decision of whether to use an abdominal
pressure belt, taking comorbidity and performance status into account. Treatment
planning was then performed in the same position, using slow-rotation serial CT
scanning (slice thickness, 2.5 mm; 4 s/slice). The gross tumor volume was defined as
the visible extent of the tumor on the CT image in the lung window. The internal
target volume (ITV) was determined from the slow-rotation CT images and from
respiratory tumor motion on the simulator. The planning target volume was defined as
the ITV with a 5-mm margin for set-up uncertainty. The SBRT plan was created with
a 3D radiotherapy planning system (CADPlan/Eclipse, Varian Medical Systems).
SBRT was delivered with a linear accelerator (Clinac 23EX, Varian Medical Systems)
using 6 MV X-ray beams with 5 to 7 non-coplanar multistatic ports and/or
multidynamic arcs.
Before June 2009, the dose calculation algorithm was based on the pencil beam
method with heterogeneity correction (modified Batho power law), and 45 Gy in 3
fractions, 48 Gy in 4 fractions, 60 Gy in 8 fractions, or 60 Gy in 15 fractions to the
isocenter was prescribed. In February 2004, we changed the prescription dose from 45
Gy in 3 fractions to 48 Gy in 4 fractions to unify the dose for the Japan clinical trial
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series. After June 2009, the dose calculation algorithm was changed to an analytical
anisotropic algorithm and 40 Gy in 4 fractions or 50 Gy in 8 fractions covering 95%
of the PTV (D95) was delivered. The median isocenter doses recalculated with pencil
beam convolution were 46.5 Gy (range: 43.2-50.7 Gy) in 4 fractions and 56.2 Gy
(range: 55.3-61.7 Gy) in 8 fractions. The choice of dose depended on tumor location
and performance status: 60 Gy in 8 fractions, 60 Gy in 15 fractions or 50 Gy in 8
fractions was selected if the lung tumor was adjacent to critical structures such as the
main bronchus, heart and great vessels, esophagus or stomach. Dose escalation was
not performed for larger tumors or metastatic tumors. This study was approved by the
ethical committee of Tohoku University Hospital and informed consent was obtained
from all patients.
Follow-up after SBRT
A clinical examination by a radiation oncologist and CT scanning were performed
4-6 weeks after SBRT to assess the pulmonary response. Thereafter, patients
underwent follow-up examinations every 3-6 months for 2 years and then every 6
months after 2 years. Patients also underwent examinations by doctors in charge of
the primary disease. Local recurrence or local failure was defined as local progression
to ≥ 1.5 times the dimensions of the original tumor [18]. FDG-PET was sometimes
performed to distinguish local recurrence from dense consolidation. The final
diagnosis of local recurrence was made by physicians and radiation oncologists.
Statistical analysis
Time to an event was calculated from the first day of SBRT to the day an event
was confirmed. Statistical analyses were performed using JMP v. 10.0.2 (SAS
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Institute). Cumulative LC and OS rates were calculated using Kaplan-Meier curves,
and a log-rank test was used to compare the curves. To analyze prognostic factors,
univariate and multivariate analyses were performed using a Cox proportional hazards
model. In these analyses, continuous variables that included missing values, such as
SUVmax and pack-years smoking, were discretely divided at the sample median and
then analyzed as categorical variables. Correlation coefficients for all variables were
calculated to avoid multicollinearity. P < 0.05 was defined as significant in all tests.
For analysis of various dosing schedules, the biological effective dose (BED10) was
calculated using the following formula: BED10 = nd [ 1 + d/(α/β) ], where n is the
number of fractions, d is the isocenter dose per fraction, and α/β ratio is 10 Gy for the
tumor. Toxicity was graded using the National Cancer Institute Common
Terminology Criteria for Adverse Events ver. 4.0.
Results
Treatment results
The median follow-up period for all patients was 35.0 months (range: 3.3-115.6
months) and that for survivors was 41.9 months (range: 3.3-105.2 months). All of the
primary sites with metastatic lung tumors were controlled at the time SBRT was
started. During follow-up, local recurrence was observed in 54 of the 229 tumors. The
median time to local failure was 14.9 months (range: 4.0-66.9 months). None the 12
tumors with mainly ground-glass components showed local failure; therefore, we had
to exclude this factor from the analysis. Of the 201 patients, 77 died of the primary
disease and 38 died of other causes. The median survival period was 43.1 months and
the median cause-specific survival period was 65.6 months. The 3-year LC, cause-9-
specific survival (CSS) and OS rates were 72.5% (95% confidence interval [CI]: 65.378.8), 70.2% (95% CI: 62.8-76.6) and 60.9% (95% CI: 53.6-67.7), respectively. The
respective 5-year rates were 67.8% (95% CI: 59.6-75.1), 51.7% (95% CI: 42.8-60.5)
and 38.1% (95% CI: 30.3-46.5) (Figure 1). There was a significant difference in LC
between the primary lung cancer curve and metastatic lung tumors curve (p=0.010,
log-rank test) (Figure 2).
Radiation pneumonitis of grades 2 and 3 occurred in 22 and 6 patients,
respectively. Steroids were administered to 14 patients. Grade 5 radiation pneumonitis
occurred in one patient who had pathologically proven interstitial pneumonia before
SBRT. The interstitial pneumonia was exacerbated after SBRT and then fatal bacterial
pneumonia were involved in.
Univariate and multivariate analyses
The results of univariate and multivariate analyses for LC and OS are shown in
Tables 3 and 4. In univariate analysis, tumor origin (primary lung cancer vs.
metastatic lung tumors; p=0.017, hazard ratio [HR]: 0.48, 95% CI: 0.27-0.87), tumor
diameter (per 1 cm increase; p<0.001, HR: 1.87, 95% CI: 1.35-2.57), SUVmax (≥ 5.9
vs. < 5.9; p=0.042, HR: 2.21, 95% CI: 1.02-5.03), date of treatment (2001-2005 vs.
2006-2011; p=0.019, HR: 1.91, 95% CI: 1.11-3.39) and prescription dose (BED10: >
105 Gy vs. ≤ 105 Gy; p=0.038, HR: 0.56, 95% CI: 0.32-0.96) were significant
predictors for LC; and gender (female vs. male; p=0.005, HR: 0.53, 95% CI: 0.330.83), tumor origin (primary lung cancer vs. metastatic lung tumors; p=0.017, HR:
0.48, 95% CI: 0.27-0.87), tumor diameter (per 1 cm increase; p<0.001, HR: 1.70,
95% CI: 1.33-2.16) and SUVmax (≥ 5.9 vs. < 5.9; p=0.004, HR: 2.12, 95% CI: 1.263.64) were significant predictors for OS. In multivariate analysis, tumor origin
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(primary lung cancer vs. metastatic lung tumors; p<0.001, HR: 0.21, 95% CI: 0.090.47), tumor diameter (per 1 cm increase; p=0.005, HR: 1.70, 95% CI: 1.17-2.45) and
prescription dose (BED10: > 105 Gy vs. ≤ 105 Gy; p=0.029, HR: 0.51, 95% CI: 0.270.93) were significant independent predictors for LC; and gender (female vs. male;
p=0.012, HR: 0.56, 95% CI: 0.34-0.88), tumor origin (primary lung cancer vs.
metastatic lung tumors; p=0.001, HR: 0.45, 95% CI: 0.28-0.73) and tumor diameter
(per 1 cm increase; p<0.001, HR: 1.70, 95% CI: 1.30-2.21) were significant
independent predictors for OS.
Subgroup analysis of metastasis from colorectal cancer
The results of a subanalysis comparing patients with metastases from colorectal
cancer and non-colorectal cancer are shown in Figure 3. The difference in LC
between the two subgroups was significant (p=0.022).
Discussion
This study was performed as a review of a single center experience of SBRT for
lung tumors. In multivariate analysis, metastatic lung tumors, increased tumor size,
early date of treatment and prescription dose of BED10 > 105 Gy were significant
factors for unfavorable LC. LC itself was associated with OS in univariate analysis
(HR: 2.02, 95% CI: 1.33-3.01, p=0.001), indicating that a strategy for improving LC
is important. For this purpose, dose escalation may be reasonable for metastatic lung
tumors or larger tumors, given the relatively low toxicity in our patients, despite the
poor pulmonary background and the presence of complications. However, this
strategy may not be applicable in all cases and may not always give the expected
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outcome because critical structures can prevent delivery and distribution of a
sufficient dose. This problem is also likely to be increased in dose escalation for
larger tumors or multiple metastatic tumors.
Prescription dose of BED10, which was divided into two categories at the sample
median (> 105 Gy amd ≤ 105 Gy), was an independent predictor. The results
confirmed previous findings [8, 14]. Prescription dose ≤ 105 Gy was often used when
the target was close to a critical structure. Thus, this strategy was relatively safe but
might contribute to relatively low LC rate because of the low prescription dose.
The date of treatment was a significant factor for LC, possibly due to
improvements in contouring (including spiculation of the GTV) and radiation
planning (introduction of the concept of the homogeneity index). Furthermore, LC
rates naturally became lower as the follow-up period became longer. The median
follow-up periods in 2001-2005 and 2006-2011 were 50.2 months and 41.6 months,
respectively, and this difference would also therefore affect the results.
We found that a metastatic lung tumor was an independent poor prognostic factor
for LC and OS. For LC, this result confirms a previous finding of Hamamoto et al.
[13] and is based on a much longer follow-up period in the current study.
The poor LC rate of a metastatic lung tumor may be the result of formation of a
metastasis. Metastatic tumor cells are the particularly potent malignancy of tumor,
which are the most aggressive cells in the neoplasm because most malignant cells
entering the metastatic process are killed, especially in the blood circulatory system
[19]. Also, in some cases, adjuvant chemotherapy or hormonal therapy is performed
after surgery. Cells with high metastatic potential are resistant to this treatment based
on genetic instability due to a several-fold increase in the rate of mutation compared
to tumor cells with lower metastatic potential [20]. This genetic instability increases
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the angiogenic and invasive potential of tumor cells, and the tumor cells escape from
immune surveillance, thus increasing the chance of metastasis. Through these steps,
and after formation of a metastasis, tumors in advanced stages develop biological
heterogeneity and increased radioresistance before and during SBRT.
Another reason for the poor LC rate of a metastatic lung tumor might be the state
of the patient. The effects of disease treatment and disease progression may lead to
cachexia and anemia temporarily or throughout the course of the disease, making the
tumor more hypoxemic. Tumor hypoxemia has been hypothesized to lead to tumor
growth and resistance to therapy because of induction of angiogenesis, genetic
mutations, resistance to apoptosis, and resistance to free radicals from radiotherapy
[21]. These changes may be one of the reasons for the poor LC of metastatic lung
tumors, but both the “seed” aspect and the “soil” aspect may be important. According
to the “seed and soil” hypothesis, metastasis is the product of interactions between
selected cancer cells (the “seeds”) and specific organ microenvironments (the “soil”)
[22]. In the lung environment, stromal products cause upregulation of P-glycoprotein
in the cells, which prompts excretion of a variety of toxic compounds, including
chemotherapeutic drugs, resulting in enhanced resistance to drugs [23]. Similarly,
through tumor-stroma interactions, some stromal products may cause increased
radioresistance of metastatic cells. If a microenvironment is changed to a rich soil due
to interactions and molecular factors, circulating tumor cells may be reseeded, as at
the primary site [24]. Therefore, modulation of a tumor microenvironment using
approaches such as antiangiogenic therapy may be effective in some metastatic cases.
In subgroup analysis, metastases from colorectal cancer showed a lower local
control curve than did metastases from non-colorectal cancer, consistent with
previous findings [12]. However, we cannot conclude that colorectal metastases are
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more radioresistant than other metastases because of the small sample size and the
variety of non-colorectal tumors, given that malignant diseases have various natural
histories. For example, our cases included two cases of metastasis from thyroid
cancer, which generally shows slow growth. Our findings do suggest that metastases
from colorectal cancer are aggressive and are likely to cause short-term local relapse.
Although our inclusion criteria for metastatic lung tumors included both
oligometastasis and oligo-recurrence, SBRT as a local therapy might be effective in
both situations. According to the Norton-Simon hypothesis, the efficacy of
chemotherapy is proportional to the growth rate of the tumor, and the growth is faster
when the tumor is not bulky. Therefore, treatment of a bulky tumor with a slower
growth rate and thus lower sensitivity to chemotherapy might make the remaining
tumor cells more sensitive to chemotherapy [25, 26]. Improvement in LC by reducing
metastases should lead to increased OS for patients including both patients with
oligometastasis and patients with oligo-recurrence.
Tumor diameter was identified as an independent factor for OS in multivariate
analysis. This was probably due to the poor LC of a large tumor and the increased
tendency for metastasis. In pulmonary resection with node dissection for clinical stage
I NSCLC, 19.4% of the patients were found to have pathologically positive nodes,
with a particularly high rate of 31.8% for unexpected positive nodes in clinical stage
IB cases [27]. Thus, this analysis showed that tumor size and solid consistency were
independent predictors for node metastasis but did not show that unexpected
pathologically positive nodes affected OS. However, in our analysis of stage I
NSCLC cases, clinical hilar lymph node or mediastinal lymph node failure was a
significant factor for unfavorable OS (HR: 1.73, 95% CI: 1.04-2.78, p=0.034). This
finding suggests that staging must be performed thoroughly before SBRT. In an
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operable case, assessment of suspicious lymph nodes by endoscopic ultrasoundguided fine-needle aspiration may be necessary. Adjunct therapy for a larger tumor
should also be considered in cases in which this is possible.
Female gender was also found to be a favorable factor for OS but not for LC. This
may be because smoking was less common in females, and this may reduce smokingrelated complications and development of another malignancy. Also, epidermal
growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) therapy for primary lung
cancer with EGFR mutation was more common in females, with 6 of 16 female
patients (37%) receiving an EGFR-TKI in the course of treatment, in contrast to only
2 of 66 male patients (3%).
Analysis of tumor consistency was not included in the study because there was no
local failure of ground-grass opacity (GGO) tumors and there was only one case in
which disease progression occurred. Most tumors with mainly a GGO component
were atypical adenomatous hyperplasia, adenocarcinoma in situ (formerly referred to
as bronchioloalveolar carcinoma) or minimally invasive adenocarcinoma, all of which
have a relatively good prognosis [28]. Thus, assessment of GGO tumors will require
more cases and longer follow-up periods. However, it may be more useful to examine
the safety of treating multiple sites by SBRT. Tumors with mainly a GGO component
are often multifocal, and for all such tumors (not limited to GGO tumors), the lifetime
incidence of a second primary tumor after surgical resection is > 10% [29]. More
cases of multi-site treatment should emerge as the outcome of SBRT improves, and
this will allow an evaluation of the safety of repetitive treatment with SBRT.
There were several limitations to this study. First, this study was a retrospective
single institute analysis with a limited sample size, the number of metastatic lung
tumors being particularly small. Second, various treatment protocols were included in
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the analysis. There were a variety of total doses, methods of dose prescription and
fractionation schema.
Conclusions
SBRT gave a high local control rate with tolerable treatment-related toxicities. Our
results suggest that dose escalation should be considered for larger and/or metastatic
lung tumors to improve the balance of benefits and risks of SBRT and to obtain better
overall survival.
List of abbreviations
SBRT, stereotactic body radiotherapy; LC, local control; OS, overall survival;
NSCLC, non-small-cell lung cancer; SUV, standardized uptake value; FDG-PET,
[18F]fluorodeoxyglucose positron emission tomography; BED, biological effective
dose; HR, hazard ratio; EGFR-TKI, epidermal growth factor receptor-tyrosine kinase
inhibitor; ECOG, Eastern cooperative oncology group; FEV1, forced expiratory
volume; UVA, univariate analysis; CI, confidence interval; MVA, multivariate
analysis; n.s.; not significant
Competing interests
The authors declare that they have no competing interests.
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Authors' contributions
TY designed the analysis, reviewed the clinical data, performed statistical analysis
and drafted the manuscript.
KJ treated the patients, reviewed the clinical data and revised the manuscript.
YS and MK treated the patients and reviewed the clinical data.
HM, TS, MK, RU, KA, NK, YI, MK, NT and KT treated patients and collected
clinical data.
YT conceived the study, reviewed the clinical data, and treated patients.
All authors read and approved the final manuscript.
Acknowledgements
We are grateful to our ex-colleagues for help with collection of data. We
particularly thank Drs. Keisuke Fujimoto, Toru Sakayauchi, Kakutaro Narazaki and
Yumi Sato for their support.
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Figures
Figure 1 - Curves of (a) LC rate and (b) CSS and OS.
(a) Local control (LC) rate and (b) cause-specific survival (CSS) and overall survival
(OS) in all patients in the study (Kaplan-Meier method).
Figure 2 - Analysis comparing local control rate with primary lung cancer and
metastatic lung tumors.
There was a significant difference in LC between primary lung cancer and metastatic
lung tumors (p=0.010, log-rank test).
Figure 3 - Subanalysis comparing patients with metastases from colorectal
and non-colorectal cancer.
There was a significant difference in local control between subgroups with metastases
from colorectal cancer and metastases from noncolorectal disease (p=0.022, log-rank
test).
- 22 -
Tables
Table 1 - Baseline patient characteristics.
Primary lung
Metastatic lung
cancer
tumor
164 patients
37 patients
201 patients
78 (range: 40-92)
63 (range: 25-85)
76 (range: 25-92)
female
39 (23%)
13 (35%)
52 (25%)
male
125 (76%)
24 (64%)
149 (74%)
0-1
142 (86%)
37 (100%)
179 (89%)
2-3
22 (13%)
0 (0%)
22 (10%)
Yes
81 (49%)
6 (16%)
87 (43%)
No
83 (50%)
31 (83%)
114 (56%)
Number
Median Age (y)
Total
Gender
ECOG performance status
History of other malignancies
Pack-year smoking
median 37.5
(range: 0-180)
Never
35 (21%)
10 (43%)
45 (24%)
< 37.5
35 (21%)
10 (43%)
45 (24%)
≥ 37.5
88 (55%)
5 (20%)
93 (50%)
FEV1, % of predicted
median 92.5
(range: 25.1-203.6)
< 92
54 (47%)
4 (66%)
58 (48%)
≥ 92
60 (52%)
2 (33%)
62 (51%)
13
0
13 (6%)
Operable
64 (39%)
20 (54%)
84 (41%)
Inoperable
100 (60%)
17 (45%)
117 (58%)
Home oxygen therapy
Operability
Abbreviations: ECOG, Eastern cooperative oncology group; FEV1, forced expiratory
volume in 1 second.
- 23 -
Table 2 - Baseline tumor and treatment characteristics.
Primary lung
Metastatic lung
cancer
tumor
172 tumors
57 tumors
Number
Tumor diameter (cm)
Total
229 tumors
2.2 (range: 0.9-4.7)
≤ 2.0
73 (42%)
27 (47%)
100 (43%)
2.1-3.0
75 (43%)
23 (40%)
98 (42%)
3.1-5.0
24 (13%)
7 (12%)
31 (13%)
160 (93%)
57 (100%)
217 (94%)
12 (6%)
0 (0%)
12 (5%)
Tumor appearance
Mainly solid component
Mainly ground-glass opacity
SUVmax on staging FDG-PET
5.9 (range: 0.6-22.8)
< 5.9
53 (50%)
4 (57%)
57 (50%)
≥ 5.9
53 (50%)
3 (42%)
56 (50%)
BED10 ≤ 105 Gy
84 (48%)
12 (21%)
96 (41%)
BED10 > 105 Gy
88 (51%)
45 (78%)
133 (58%)
2001-2005
76 (44%)
39 (68%)
115 (50%)
2006-2011
96 (55%)
18 (31%)
114 (50%)
Prescription dose
Date of treatment
Abbreviations: SUVmax; maximum standardized uptake value, FDG-PET;
[18F]fluorodeoxyglucose positron emission tomography, BED10; biological effective
dose calculated using α/β = 10.
- 24 -
Table 3 - Univariate analysis for local control (LC) and overall survival (OS).
UVA for LC
UVA for OS
Variables
HR (95% CI)
P value
HR (95% CI)
P value
Age (per 10-y increase)
0.95 (0.80-1.15)
0.617
0.93 (0.80-1.11)
0.428
Gender (female vs. male)
0.66 (0.34-1.19)
0.177
0.53 (0.33-0.83)
0.005*
Performance status (0-1 vs. ≥ 2)
1.19 (0.52-3.43)
0.703
0.86 (0.50-1.58)
0.619
0.48 (0.27-0.87)
0.017*
0.53 (0.34-0.84)
0.007*
0.70 0.38-1.21)
0.212
0.83 (0.56-1.20)
0.331
1.38 (0.77-2.51)
0.266
0.85 (0.57-1.26)
0.426
0.68 (0.38-1.19)
0.185
0.76 (0.52-1.12)
0.173
1.01 (0.49-2.05)
0.972
0.84 (0.51-1.36)
0.494
1.87 (1.35-2.57)
<0.001*
1.70 (1.33-2.16)
<0.001*
2.21 (1.02-5.03)
0.042*
2.12 (1.26-3.64)
0.004*
1.91 (1.11-3.39)
0.019*
1.36 (0.93-1.99)
0.106
0.56 (0.32-0.96)
0.038*
0.94 (0.65-1.37)
0.760
0.85 (0.34-1.78)
0.689
0.72 (0.40-1.22)
0.225
Tumor origin (primary lung cancer vs.
metastatic lung tumors)
History of other malignancies
(yes vs. no)
Pack-year smoking
(≥ 37.5 vs. < 37.5)
Operability
(operable vs. inoperable)
FEV1, % of predicted
(≥ 92% vs. < 92%)
Tumor diameter
(per 1 cm increase)
SUVmax
(≥ 5.9 vs. < 5.9)
Date of treatment
(2001-2005 vs. 2006-2011)
Prescription dose
(BED10: > 105 Gy vs. ≤ 105 Gy)
radiation pneumonitis
(≥ 2 vs. < 2)
- 25 -
Abbreviations: UVA, univariate analysis; LC, local control; OS, overall survival; HR,
hazard ratio; CI, confidence interval; FEV1, forced expiratory volume in 1 second. * p
< 0.05
- 26 -
Table 4 - Multivariate analysis for local control (LC) and overall survival (OS).
MVA for LC
MVA for OS
Variables
HR (95% CI)
P value
HR (95% CI)
P value
0.56 (0.34-0.88)
0.012*
Gender
n.s.
(female vs. male)
Tumor origin (primary vs.
0.21 (0.09-0.47)
<0.001*
0.45 (0.28-0.73)
0.001*
1.70 (1.17-2.45)
0.005*
1.70 (1.30-2.21)
<0.001*
1.50 (0.66-3.61)
0.331
1.41 (0.81-2.48)
0.218
0.51 (0.27-0.93)
0.029*
n.s
2.22 (1.19-4.23)
0.011*
n.s
metastatic lung tumors)
Tumor diameter
(per 1 cm increase)
SUVmax
(≥ 5.9 vs. < 5.9)
Prescription dose
(BED10: > 105 Gy vs. ≤ 105 Gy)
Date of treatment
(2001-2005 vs. 2006-2011)
Abbreviations: MVA, multivariate analysis; LC, local control; OS, overall survival;
HR, hazard ratio; CI, confidence interval; n.s., not significant. * p < 0.05.
- 27 -
Figure 1
Figure 2
Figure 3